Device for scanning a drawing and for printing a drawing paper with a corresponding pattern

ABSTRACT

A device for scanning a drawing and/or for printing a drawing paper with a pattern corresponding to said drawing, which comprises a support for holding the drawing and/or the drawing paper; a scanning head for generating electrical signals corresponding to said drawing, and/or a printing head which is fed the corresponding electrical signals for printing the pattern; means for generating relative motion between said support and the scanning head and/or the printer head in one direction; means for generating relative motion between support and scanning head and/or printer head in another direction, normal to the first; one electronic trigger generator for the generation of scanning and/or printer trigger signals when a point of the drawing should be scanned or when a point of the pattern should be printed; one release circuit for the successive release of a given number of scanning and/or printer trigger signals; and another release circuit for connecting the means for the relative motion in the second direction during such time intervals in which the scanning and/or printer trigger signals are not released.

United States Patent [191 Schnattinger et al.

[ Oct. 23, 1973 DEVICE FOR SCANNING A DRAWING AND FOR PRINTING A DRAWING PAPER WITH A CORRESPONDING PATTERN [75] Inventors: Walter Ludvig Schnattinger,

'Eriskirch-Schlatt; Albert Seelos,

Heinz Mayer; Reinhold Oelm ayer, all of Kaufbeuren; Josef Duel],

Oberbeuren; Willieim Hertl, Kaufbeuren; Hans-Jorg Koch, Stuttgart-Bonlanden; Hans-Joachim Stock, Freiberg, all ot Gerinany [73] Assignee: Firma Franz Morat GmbI-I,

Stuttgart-Vaihingen, Germany 22 Filed: Dec. 29, 1971 211 Appl. No.: 213,590

3,404,221 10/1968 Loughren l78/5.2 R

Primary Examiner-Richard Murray Attorney-John Lezdey et al.

[57] ABSTRACT A device for scanning a drawing and/or for printing a drawing paper with a pattern corresponding to said drawing, which comprises a support for holding the drawing and/or the drawing paper; a scanning head for generating electrical signals corresponding to said drawing, and/or a printing head which is fed the corresponding electrical signals for printing the pattern; means for generating relative motion between said support and the scanning head and/or the printer head in one direction; means for generating relative motion between support and scanning head and/or printer head in another direction, normal to the first; one electronic trigger generator for the generation of scanning and/or printer trigger signals when a point of the drawing should be scanned or when a point of the pattern should be printed; one release circuit for the successive release of a given number of scanning and/or printer trigger signals; and another release circuit for connecting the means for the relative motion in the second direction during such time intervals in which the scanning and/or printer trigger signals are not released.

30 Claims, 14 Drawing Figures PAIENIEUUBI23 191s 3.767.844

SHEET 10F 9 FIG. 7

PATENTEDUU 23 I975 SHEET U 0F 9 FIG. 4b

FIG. 40

PATENTEUHU 23 ms 3. 767 844 SHEET 8 BF 9 FIG. 6

DEVICE FOR SCANNING A DRAWING AND FOR PRINTING A DRAWING PAPER WITH A CORRESPONDING PATTERN The invention relates to a device for scanning and/or printing a copy, containing a scanning and/or printing head, a drum as the carrier of the copy and a device by means of which a relative movement can be produced in two directions at rightangles to one another between the scanning head or printing head and the drum.

From British Patent Specification 1,190,600 a device is known for the simultaneous scanning and printing of a copy. This known device contains a common large drawing table over one-half of which a scanning head can be conveyed for scanning an artists drawing and over the other half of which a printer head can be conveyed for the simultaneous printing out of a design pattern corresponding to the artists drawing. The course of the movements takes place in the known device in that first of all the scanner head or printer head are moved jointly in the line direction, then by one space between lines in the column direction and then once again in the line direction. For the purpose of carrying out the various movements step motors are used. The scanning of the artists drawing takes place with the help of a lamp operated by impulses which is controlled for a short time when scanner head is at a standstill.

In a scanning device known from British Patent Specification 1,01 1,605, on the other hand, one uses as support for the artists drawing a drum which is scanned along a circumferential line whilst at a standstill in that a scanner head mounted on a carriage is first of all adjusted on to a given circumferential line and then the drum is turned step by step until the entire circumferential line has been scanned, and then the scanner head is set on a new circumferential line.

A disadvantage with these known devices is the fact that because of the different courses of movement only relatively low scanning or printing speeds can be achieved. Consequently the problem of the invention is to avoid this disadvantage and to provide a device which can be used with a comparable speed both for scanning and also for printing.

Starting off from the device referred to at the beginning, the invention is characterised by an electronic clock generator which can be switched on and off whilst the drum rotates continuously for the purpose of producing a scanning and/or printing stroke and an electronic clock generator which can be switched on and off for the purpose of controlling a motor which conveys the scanner or printer head in the axial direction of the drum.

The most important difference between the invention and the known devices consists in the fact that the scanning and/or printing is carried out during the continuous transportation of the copy, and when this happens the switching on and off of the one clock generator on the one hand determines that part of the circumferential surface of the drum which is to be scanned or printed, and on the other hand stroke impulses are released with a previously decided frequency which determine the speed of scanning or printing, the number of the points to be scanned or printed and the size of these points. Furthermore, the other clock generator controls a motor which brings about the advance of the scanning and/or printing head after the scanning or printing of a complete line of the copy. According to the invention the advance can take place either during a second rotation of the drum, during which no scanning or printing takes place, or in a section of the drum circumference which is not covered with the copy. The speeds which can be achieved by the invention are at least 1,000 Hz for the scanning and at least 200 Hz for the printing with a circumferential speed of the drum of about 1 m./sec.

For the simultaneous scanning and printing along the lines of the device according to British Patent Specification 1,190,600 it is possible to provide two drums on one of which the scanning is carried out and on the other the printing is carried out. In an advantageous further development of the invention, however, the scanner head and the printer are mounted on the same drum.

In a further form of execution of the invention only one carriage is provided on the drum, on which as desired it is possible to mount either the scanner head or the printer head. This form of execution is suitable for those processes in which two different drums are used either for scanning and printing and in which the scanning operation takes place in a stage of the process which is independent of the printing operation.

For the further improvement of the various forms of execution according to the invention it is proposed that the copy be fitted in the circumference of the drum in such a way that a part of the surface of the drum remains free. This expedient makes it possible to carry out the advance of the carriage in the axial direction on each occasion in that section of time during which the free part of the circumference of the drum travels past the scanner head or printer.

The invention is described below in conjunction with the drawing on the basis of a special example of execution.

FIG. 1 shows diagrammatically the overall structure of the device according to the invention.

FIGS. 2 and 2a show details of the scanning and printing device.

FIGS. 3, 3a and 3b shows the nature and manner in which the scanned signals are stored.

FIGS. 4a and 4b show the different phases during the scanning or printing operation when using the scanning and printing device represented in FIG. 2.

FIG. 5 shows diagrammatically the circuit arrangements necessary for transferring the scanned signals into the storage device.

FIG. 6 shows a part of the logic used in the device according to FIG. 5.

FIG. 7 shows in diagrammatical form the circuit arrangement which is necessary for converting the items of information stored in the storage device into control signals for the printing device.

FIGS. 8, 8a and 8b show in diagrammatical form a central control unit and parts thereof.

FIG. 1 shows in diagrammatical form the overall structure of a device according to the invention for the automatic scanning of a freely drawn drawing, the socalled artists drawing 1, and for the automatic printing out of a drawing composed of individual colour dots,

the so-called design pattern 10. The artists drawing 1,

like the design pattern 10, is generally drawn in a number of colours, but it can also consist of zones with different tones of grey or the like if these lead to different reflection or transmission behaviours. Furthermore the artists drawing 1, like the design pattern 10, generally possesses the size of a motif or repeat, that is to say it displays the smallest regularly recurring pattern, for example, of a textile article or of a mosaic picture.

During the scanning operation the artists drawing 1 is scanned line by line by means of an optical/electrical scanning head 2. The scanning signals so obtained are assessed in an assessment circuit 3 and/or classified and are then fed via coding an decoding unit 4, a buffer storage 5 and a logic 6 to a storage unit 7 in which they are stored permanently in digital form.

During the printing operation the items of information stored are first of all read out of the storage device 7 and then via the logic 6, the buffer storage 5 and the coding and decoding unit 4 they are fed to a printer 9, which prints a drawing paper point by point and in this way produces a design pattern 10 corresponding to the artists drawing but consisting of a large number of individual dots after the fashion of a screen, each screen dot being printed in a single colour. The individual dots of the finished design pattern 10 are, for example, allocated to one stitch of a knitted article or to one mosaic stone of a mosaic picture.

By comparing the design pattern 10 with the original artists drawing 1 the designer can determine whether the knitting pattern or mosaic picture equivalent to the design pattern 10 corresponds to his ideas in an optimum manner or Whether there are still alterations to be made. After such alterations have been carried out (for example the point by point correction of the design pattern 10) and after wiping out the items of information stored during the scanning of the artists drawing, the design pattern 10 is then scanned so that in the storage device 7 it is now the information corresponding to the corrected design pattern 10 which is stored. The operations described can be repeated as often as is necessary until during the printing operation a design pattern 10 is printed out which appears to be optimum, which is the same thing as saying that the stored information which is to be used later on for other purposes corresponds exactly with the desired design pattern 10.

In order to avoid its being necessary for the entire design pattern 10 to be re-scanned and stored every time, it is provided according to the invention that the information fed into the storage device 7 is provided with addresses. In this way it is possible to correct the stored information stage by stage. Preferably measures are provided which permit of an exchange of all those items of information which are allocated to a preselected line of the design pattern 10.

Between the printer 9 and the storage device 7 it is possible, according to the construction of the printer, also to insert delayed stages 11 and 12 in order to delay in relation to one another the items of information corresponding to the individual colours.

Ifit is found that the stored items ofinformation read exactly to the desired design pattern, the storage device 7 is read out once again. The items of information read out are used via the buffer storage 5 and further devices not shown in the drawing either for the direct control ofa machine 13 reproducing the design pattern 10 or are fed to a device 14 for the production of a control strip which is suitable for the electronic control of such machines.

Between the assessment circuit 3 and the storage device 7 or between the storage device and the machine or of device 14 it is also possible to insert a device 16 in order to bring the signals into a desired order, which is known in knitting technology, for example, as transposition.

With the device described on the basis of FIG. 1 it is possible in the same way to scan artists drawings 1 which have been drawn without screen processing and screen-processed design patterns 10. Furthermore it contains devices which will be described later on and by means of which it is possible to carry out changes of scale, that is to say an artists drawing 1 can be stretched or compressed as desired over its entire width or height. This advantage makes it possible on the one hand to print with a constant dot size and on the other hand also to assess an artists drawing if it has been drawn on a wrong scale or on a scale which is not pleasant visually. Since furthermore the scanning of an artists drawing 1 is equivalent to the scanning ofa design pattern 10, reference will only be made below to the artists drawing 1 during the scanning operation.

During the scanning operation the artists drawing 1 is stretched on to a drum 101 mountes so that it can rotate (FIG. 2), for example in such a way that its Y axis runs parallel to the axis of the drum and its X axis runs at right angles to the axis of the drum in the circumfer ential direction of the drum 101. On two rails 103 running parallel to the axis of the drum there is mounted a carriage 105 so that it can slide and which can be moved backwards and forwards by means of a stepping motor 107 in the Y direction along a generatrix of the drum 101. The scanning head 2 is mounted on the carriage 105.

Before the commencement of the scanning, the scanner head 2 is set at the beginning of the first line of the artists drawing running in the direction X, so that during the first effective rotation of the drum the first line is scanned. At the end of the first line or of each successively scanned line so many stepping impulses are fed to the stepping motor 107 that the scanner head is located at the beginning of the next rotation of the drum exactly over the commencement of the next line of the artists drawing 1 to be scanned.

During the printing operation the paper to be printed is stretched accordingly on the surface of the drum in such a way that its Y axis runs parallel to the axis of the drum and its X axis runs in the circumferential direction of the drum 101. The printer 9, on the other hand, is mounted on the carriage 105. As is the case during the scanning, the paper to be printed is printed line by line until the pattern 10 is finished. The printer 9 is preferably equipped with printing pins 919 at a distance from one another in the X direction.

In order to achieve as high as possible a scanning speed, the scanning according to the invention is carried out in a completely automatic continuous process, in which during the entire scanning or printing operation the drum 101 is rotated continuously by means of a stepped or synchronous motor 109 and an intermediate gear lll, and the carraige 105 is moved forwards step by step.

The gear 111 can be designed as a change-over gear for adjusting a number of circumferential speeds of the drum 101. However, the adjustment of different rotation speeds of the drum 101 can be carried out by purely electrical means, as is described later on on the basis of the central control unit (FIG. 8). The correct adjustment is carried out preferably when actuating the keys scanning or printing.

According to FIG. 2a, the printer 9 preferably contains several permanent magnets 91 1 which are fixed to a common support and into the air gap of each of which there projects a moving coil 913, to which a pin 915 is fixed, which is mounted so as to slide in a guide 917. At the other end of each pin 915 there is fixed a printer pin 919 which contains a tube 921, at the outer end of which there is provided a printing nib 923 made of felt or fibre material. Immediately adjoining the printer tip 923 in the tube 921 there is an insert 925 made of absorbent ceramic, felt or fibre material, with which a flexible pipe 927 is connected, which leads to an ink container 929.

The flexible pipes 929 are also filled according to the invention with a suitable fibre material and absorbent material, such as for example cotton wool, is preferably also provided in the ink container 929. As fibre material it is possible to use the width material which is usually employed in felt ends. Because of the wick action and the fact that at no point in the path of flow a free flow of the ink is possible, the feed of ink to the printer tip 923 takes place extremely uniformly. Even when a printer tip is unused for a long time during a printing cycle, no troublesome drops ofink occur when printing starts again nor any empty places caused by drying out. Before a renewed use after a very long period of standstill it is sufficient to dip the printer tips briefly in spirit.

The restoration of the moving coils 913 after a deflection can be carried out as in the case of loudspeakers by mechanical means or electrically by means of a push-pull circuit.

A further improvement in the application of ink is achieved by not directing the printer pins to the same point and therefore setting them obliquely, but aligning them in such a way that the printer tips when in the pushed-forward position are at a distance from one another along a straight line or on an arc of a circle.

The advance of the carriage 105 is to be carried out in a period of time during which scanning or printing are not carried out at the same time. In the form of execution described here, therefore, the circumference of the drum is greater than the maximum possible extent of the artists drawing 1 in the X direction. As a result of this, during the scanning or printing there is always a part of the circumference of the drum free between the end of one line and the beginning of the next line so that the Y advance can always be carried out whilst this free part is passing by the scanner head 2 or the printer 9. According to other forms of execution, the drum 101, so that there is sufficient time left for the Y advance, after the scanning or printing of one line can be allowed to rotate once more and during this second rotation the scanning or printing operation is blocked, or both forms of execution can be used in conjunction with one another, if for example the scanning operation takes place considerably more rapidly than the printing operation.

On the axis of the drum there are mounted rotatable signal discs 113, 115 with gap or hole markings 117, 1 19, which are scanned with optical/electrical scanning devices 121, 123, or any other signal transmitters. The markings 117, 119 can be adjusted accurately on the beginning of the line or the end of the line of the artists drawing 1, so that the scanning devices emit an electrical signal during each rotation of the drum 101 at the beginning of the line or at the end of the line. Below it will be assumed that the marking 117 is adjusted to the beginning of the line and the marking 119 is adjusted to the end of the line. The signal produced by the marking 117 is therefore designated as the MZA signal (mechanical commencement of line) and the signal produced by the marking 1 19 is designated as the MZE signal (mechanical end of line).

On the frame supporting the drum 101 there is provided a connecting'plug for a cable 125, in which all the leads are fitted by means of which the voltages, signals etc. required for the operation of the drum or produced during the operation of the drum are fed in or collected.

According to one form of execution of the invention, the carriage 105 possesses a guide 127 into which it is possible to insert as desired either the scanner head 2 or the printer 9. A screw 129 is used to fix it. According to another form of execution, it is possible to provide two separate drums 101, which are only used either for the scanning operation or for the printing operation. According to further forms of execution of the invention it is possible to arrange a second carriage 105 on the rails 103, which is transported by the same or a different stepped motor 107 in the Y direction. This arrangement is advantageous if it is desired to scan and print simultaneously. Finally, it is also feasible to arrange the carriage for the scanner head on the front of the drum and the carriage for the printer on the back of the drum.

For the purpose of scanning the artists drawing 1 it is possible to use a scanner head 2 according to British Patent Specifications 1,170,947 and 1,190,093, to which reference is expressly made here. Such scanner heads serve to pick up the light reflected from the illuminated artists drawing and contain in the main three photo-diodes and three colour filters arranged in front of these, through which there is fed to each photoelectric cell only the light from a narrow range of wavelengths (for example blue, green, red). The photodiodes have preliminary amplifiers connected up after them, which are brought to the same output level for the white basic colour of the artists drawing 1. The digital conversion of the analog signals which appear at the outputs of the preliminary amplifiers is carried out by post-amplifiers with suitably variable threshold values in the separation circuit 3 arranged after the scanning head 2, which possesses three outputs 31 (FIG. 1) corresponding to the three photo-diodes. In the case of a four-colour artists drawing (blue, green, red, white), when scanning a blue, green or red point there occurs a signal at one of the three outputs, whereas when scanning a white point a signal appears simultaneously at all three outputs. In the case of the additional use of the colours turquoise, lilac and yellow, when such a colour is scanned signals appear at two outputs of the separation circuit 3. These signals are fed to the coding and decoding unit 4. V

In the coding and decoding unit 4 the items of colour information which correspond to the possible conditions at the outputs 31 have binarily coded words allocated to them. When four colours are used, words are sufficient fo this purpose with two bits each, such as for example 1 l for colour 1, 10 for colour 2, 01 for colour 3 and 00 for colour 4. Since further items of information are stored in addition to the colour combinations, each of these words is enlarged still further by one bit in the logic 6, so that in all three-digit words occur. In order to increase the reliability in avoiding error it is also possible to use parity bits. Finally it is possible to record each word twice. Since coding and decoding units are adequately known, we shall refrain from describing any further details.

According to one example of execution of the invention, one uses as storage unit a magnetic tape 701 (FIGS. 3, 3a, 3b), because this is advantageous for reasons of cost. However, in order to ensure that the magnetic tape can be used for the direct control, for example, of a knitting machine operating at 1,000 Hz, the recording of the items of information on the magnetic tape must be carried out in a special manner.

According to FIG. 3 the magnetic tape 701 is recorded blockwise, each information block 703 recorded containing all the items of information regarding one line of the artists drawing 1. In FIG. 3 the information blocks 703 are numbered consecutively from 1 to y in order to show the order of sequence in which they are recorded. Accordingly, whilst the magnetic tape 701 is travelling forwards (arrow V) the first half 1 to Y/2 of all the information blocks 703 is recorded, whilst the remaining y/2 l to y information blocks 703 are recorded during the return travel (arrow R). At the end of each information block 703 a special symbol is recorded. This special symbol has the meaning end of line in the information blocks 1 to y/2I and y/2 l to y-l, and indicates the end ofa line in the artists drawing 1 (ZE symbol 705 in FIG. 3a). A special symbol which is written at the end of the last information block y/2 recorded during forward running means that the half of all the lines of the artists drawing 1 have been recorded. This special symbol is referred to below as first y/2 symbol, and the electrical signal allocated to it is referred to as the first y/2 signal." A symbol 709 which is identical in coding with the y/2 symbol (FIG. 3a), which is referred to below as the second y/2 symbol is recorded during the return travel at the end of the last information block. It indicates that now all the lines of the artists drawing 1 have been scanned and recorded.

Since a three-digit binary word is allocated to each special symbol and each colour information, both during forward running and return running of the magnetic tape 701 three tracks are required. A further track each during forward running and return running is required in order to write an address between the information blocks which during the correction of the design pattern serves to find the information block allocated to a given line and to replace it by a new information block. This is advantageous if the pattern has, for example, 500 or 1000 lines, but only a few lines have to be corrected.

Finally a ninth track of the magnetic tape 70] is required in order to record synchronisation symbols 711 during forward running (FIG. 3a) and which are read during the return running of the tape and make it possible for the information blocks written during the return running to be arranged essentially at the same place as the information blocks written during the forward running. Instead of a synchronisation symbol, however, it is also possible to use for this purpose the line end and y/2 symbols.

The subdivision of the requisite tracks is, for example, as follows:

forward track 1 track 3 track 5 track 7 track 9 running return track 2 track 4 track 6 track 8 running colour 1 l 1 l 0 0 colour 2 l 0 1 0 0 colour 3 0 l l O 0 colour 4 0 O l 0 0 line end 1 l 0 0 O y/2 I O 0 O O A O l 0 l I The A symbol 712 (FIG. 3a) means that the address of an information block immediately follows this symbol.

The address for a given information block is in each case suspended on the previous information block for the purpose for the simplification of the entire device. This means that the first information block is immediately followed by the address for the second information block and the last information block is immediately followed by the address for the first information block. If, therefore, during a search the tape is stopped after finding the address looked for, it is possible to begin immediately with the recording or the reading out of the desired information block. In FIG. 3a, for example, an information block 703 is represented, which is written during forward running and consists of the words for four colours F1 to F4, a line end symbol, an address symbol and a four-letter address. FIG 3b, on the other hand, shows the last information block recorded during return running, which differs from the information block according to FIG. 3a by the y/Z symbol and a different addressv This information block also begins where the synchronisation symbol 711 of the information block 703 allocated to it and recorded during forward running is located.

If the motif, and consequently the artists drawing 1 or the pattern 10 consists of an odd number of lines, then in order to maintain the written organisation, an empty block 713 is formed at a defined place which can be seen from FIG. 3, which it is true is located at the same place as the information block y/2 1, but pos sesses no information in any single track.

When entering and reading back the magnetic tape is operated by a start/stop mechanism, that is to say during the recording of an information block or empty block 703 or 713 it is transported continuously past the recording/reading threads which are not shown in the drawing and is kept so long there until all the symbols are available which are necessary for the entry into storage of an information block. At the end of the y/Z- th information block it is switched over from forward running to return running by the first y/2 signal and then the recording of the remaining information blocks commences in the same way as during forward running. As a result of the second y/2 signal it is switched over once again from return running to forward running.

After this the recording! reading heads for the tracks 1, 3, 5, 7 and 9 must be located at a point in the magnetic tape 701 which is located in front of the first information block, so that during the next start of the magnetic tape 70] (reading cycle or correction) the entire first information block is included. Since at the starting or stopping of the tape, however, different time intervals are required and these time intervals can also vary, this must be ensured by special measures, for example the synchronisation symbols according to the invention in track 9, which according to FIG. 3a are located in the same placd as the address symbols 712. During the return running of the magnetic tape 701, the reading head for the track 9 is switched on, which then always produces a synchronisation signal if the magnetic tape has a synchronisation symbol 711 in track 9. The synchronisation siganls then act via a gate to release the entry into storage of the next information block, so that the information blocks y/2 l to y begin and end practically where the information blocks 1 to y/2 begin and end. On the basis of the addresses and of the time interval which is required for stopping the tape, there also occurs the switching over from forward running to return running or vice versa by the two y/2 symbols in such a way that during the next starting of the tape the entire following information block is included.

The circumference of the drum 101 (FIG. 2) according to one form of execution of the invention is so much larger than the maximum possible width of the artists drawing 1 or pattern in the direction X so that during the period of time in which the uncovered part of the drum 101 runs past the scanning head 2 or the printer 9, the scanned information can be placed on the magnetic tape 701 (scanning operation) or a stored information block 703 can be read out and processed in such a way (printing operation) that all the control signals necessary for a line can be made available to the printer as the drawing paper travels past.

The phases arising from this during the scanning or printing are represented diagrammatically in FIGS. 4a, b.

FIG. 4a shows the scanning operation in which the drum 101 is rotated in the direction of the arrow P, the

scanning head 2 is mounted on the carriage 105 and the artists drawing 1 is stretched on a part of the circumference of the drum.

During a phase A one line of the artists drawing is scanned during each rotation of the drum. The phase A is introduced by the MZA signal (FIG. 2) produced by the marking 117. The scanning signals obtained are pushed into the temporary storage 5 and are transmitted to the magnetic tape 701 during a phase B which is introduced by the line end signal. It is true that the line end signal corresponds in time to the MZE signal produced by tne marking 119, but it is electronically produced. The phase B is ended by an address end signal produced by another counter, which indicates that the information block corresponding to one line of the artists drawing and also the address for the next information block have been placed on the magnetic tape 701. In a phase C, which is located between the address and signal and the MZA signal, there is no scanning nor recording on the magnetic tape 701. During the phases B and C there also takes place the setting of the carriage 105 to the next line of the artists drawing. The duration of the phases A, B and C depends on the width of the artists drawing 1 in the direction X and the time necessary for adjusting the carriage 105.

During the printing operation, according to FIG. 4b the drawing paper is stretched on the drum 101 which is rotated in the direction of the arrow P, and which after the printing operation forms the design pattern 10. The printer 9 is mounted on the carriage 105. After a start signal which is produced by means of a hand switch on the occasion of the first start and then afterwards is alwys produced by a counter after the printing out of a complete line as a printing end signal, the reading out of an information block 703 on the magnetic tape 701 commences and the feed of this information block into the temporary storage 5.

The phase D is ended by a signal which is produced by a comparison counter of the temporary storage unit and indicates that the information block is ready for the printing operation in the temporary storage unit 5. This signal will be referred to below as the comparison/- counter/printing signal. In a phase E, which depends upon the length of a line of the design pattern 10, nothing happens. When the next MZA signal appears, a phase F then begins, in which the information which is ready in the temporary storage unit 5 is printed out. The end of printing signal then introduces the reading of the next information block and the moving of the carriage forward by one line.

Below the temporary storage unit 5 is described which is surrounded by a broken line in FIGS. 5 and 7. The temporary storage unit 5 receives from the central control unit 8 (FIG. 8) the necessary control signals or supplies these signals to it.

FIG. 5 shows those parts of the temporary storage unit 5 which are required for the scanning operation, all the unessential parts or the parts which are obvious to the technician being omitted.

The temporary storage unit 5 contains as essential components two shift registers 501 and 503 which preferably contain at least as many storage elements as is derived from the sum of the screen dots of a line and the bits necessary for the special symbols and addresses.

The words formed in the coding and decoding unit 4 are offered to the two shift registers 501/503 parallel to the two information inputs. To the clock inputs of the shift registers 501, 503 it is possible to feed via an OR member 505 the impulses of the scanning clock (AT) formed at the output AT of the central control unit 8. The output of the OR member 505 is also connected with the counter input of a comparison counter 507 which is adjusted in a fixed manner to the number of the storage cells of the shift register 501, 503 and gives a comparison/counter/scanning signal when this number is reached.

With the clock inputs of the shift registers 501, 503 and the counter input of the comparison 507 there are also connected via the OR member 505 the outputs of two clock generators 509 and 511, the clock generator 509 supplying impulses with a relatively high sequence frequency (rapid stroke, for example 40 KHZ) and clock generator 511 supplying impulses with a relatively smaller sequence frequency (recording stroke, for example 8 KHZ), the latter being fed also as counter clock signals to an input ZT of the central control unit 8.

Line end or y/2 outputs of the central control unit 8 at which the line end or y/2 signals appear are connected via an OR member 513 which a start input of the clock generator 509, the stop input of which is connected with the output of the comparison counter 507.

The output of the comparison counter 507 is also connected via a delayed action stage 515 on the one hand with the comparison counter scanning input of the central control unit 8 and on the other hand via an AND member 517 and an OR member 519 with the start input of the clock generator 511. The other input of the AND member 517 is attached to the output Q1 of a flip-flop 521 whose clock input is connected with the output y/2 of the central control unit 8 and whose output O2 is connected via a further AND member 523 with the other input of the OR member 519. The other input of the AND member 523 is connected to an output S of the storage device 7, from which the synchronisation signals stored in a track 9 are taken.

The output of the comparison counter 507 is finally also connected with the start input of the storage device 7 and, via the delayed action stage 515 and an OR member 525 with a restoring input R.

The stop input of the storage device 7, the stop input of the clock generator 511 and the other input of the OR member 525 are connected with the output of an address counter 527. The address counter 527, a binary counter 529 and a shift register 531 serve for writing in the particular address. The input of the binary counter 529 is connected with the line end output of the central control unit so that it is set by the end of line signals at each case to the address of the next following information block. As its initial position is the number 1, it is adjusted to the address of the second line by the end of line signal appearing after the scanning of the first line, so that this second line is suspended on the first information block. Correspondingly, the binary counter 529 is set to the address of the first line by the end of line signal of the last line, so that the first line is suspended on the last information block 703.

The binary counter 529 feeds the address set into the shift register 531, from which it is transferred by the time signals coming from the clock generator 511 to tracks 7 or 8 of the magnetic tape when an AND member 533 is accordingly prepared by the output Q2 of a flipflop 535. The input S2 of this flipflop is connected via a delayed action stage 537 with the counter stop output of the central control unit, whereas the input S1 is connected to the output of the address counter 527, which is also located on its return input.

With the output of the AND member 533 there is also connected the input of the address counter 527, so that it also counts those strokes which are fed to the clock input of the shift register 531. The address counter is set to the number of bits which each address comprises, thus for example the number 9 or if 500 or 1000 screen dots are to be addressed per line. As a result of the end of address signal appearing at the output of the address counter the comparison counter 507 is also set back and the magnetic tape is halted.

The storage device 7 has an input which is connnected with the output y/2 of the central control unit 8 via a delayed action stage 539. This input leads to a switch which is not shown in the drawing, which carries out the switching over from forward travel to return travel on the appearance of the first y/2 signal and the switching over from return travel to forward travel on the appearance of the second y/2 signal.

The outputs of the shift registers 501 and 503 are connected with two inputs of the logic 6. Further inputs of the logic are connected with the counter stop, y/2 and line end outputs of the central control unit 8. The tracks 1, 3, 5 and 9 of the magnetic tape 701 are recorded via the four outputs of the logic 6 during forward running, whilst the tracks 2, 4 and 6 are recorded during return running.

A further input of the logic 6 is connected with an UZ output (odd number of lines) of the central control unit 8. When the odd number of lines signal appears, an empty block 713 (FIG. 3) is recorded.

The logic 6 serves to prepare the signals required in the recording operation for the recording heads of the storage units 7 or during the printing operation to feed the information read out from the storage device 7 in the requisite order and sequence to the temporary storage 5. FIG. 6 shows diagrammatically that part of the logic 6 which is necessary for the recording operation. The part necessary for the printing operation is similarly constructed with the flow of information in the opposite direction.

According to FIG. 6 each input of two OR members 601 and 603 is connected with one of the outputs of the shift registers 501 and 503. To each other input of the OR members 601, 603 there are fed the output signals of an AND member 605, the one input of which is connected with the output Q2 of a flipt'lop 607 and the other input of which is connected to the counter stop output of the central control unit. A third input of the OR member 601 is connected with the output of an AND member 609, whose one input is connected with the output Q1 of the flipflop 607 and whose other input is connected with the counter stop output of the central control unit 8. The two inputs S1 and S2 of the flipflop 607 are connected with the end of line output or via a delayed action stage 611 with the y/2 output of the central control unit 8.

The outputs of the AND member 605 and 609 are connected with two inputs of an OR member 613, the third input of which is connected via a delayed action stage 615 with the counter stop output of the central control unit 8, the output of which has a reversing stage 617 connected after it.

The part of the logic 6 shown in FIG 6 possesses four outputs shown diagrammatically, at which the signals to be fed to the tracks 1, 2 or 3,4 or 5, 6 or 9 are statically ready in the correct order of sequence and are scanned via gates with the recording stroke developed by the clock generator 511 (FIG. 5).

The delayed action stage 611 is intended to ensure that in the event of a y/2 signal appearing, this is delayed in relation to the end of line signal which appears almost simultaneously by the amount by which the output Q2 of the flipflop 607 is set. The delayed action stage 615, on the other hand, must delay the counter stop signal by exactly one stroke, so that when the counter stop signal appears the special symbol end of line or y/2 is first of all recorded in the tracks 1 to 6 and then the special symbol A is recorded in the next stroke. At the same time as the address symbol, the synchronisation symbol is recorded in track 9 during forward running. The switching over to the different recording or reading heads takes place automatically during the switching over of the storage unit 7 from forward travel to return travel or vice versa.

FIG. 7 shows those parts of the temporary storage 5 which are required for the printing operation, and once again all the unessential parts have been omitted. Furthermore, in order to make it easier to understand, the part of the temporary storage 5 required for the printing operation is represented in FIG. 7 as a system independent of the part according to FIG. 5 required for the scanning operation. Many of the components of the temporary storage unit 5, for example the shift registers S01 and 503, however, can be used both during scanning and during printing.

The part of the temporary storage 5 necessary for the printing operation contains as essential components four shift registers 551, 553, 555 and 557, which preferably have the same number of storage cells as the shift registers 501 and 503. The information inputs of the shift registers 551 and 555 or 553 and 557 are in each case connected in parallel, but an information barrier 559 is arranged in front of the information inputs of the shift registers 555 and 557. As a result of the information barrier 559 the information inputs of the shift registers 555 and 557 are kept free from information at certain intervals of time without the shift stroke fed to the stroke inputs being interrupted. The information inputs of the shift registers are located on the two information outputs of the logic 6, to which there are offered serially the words stored on the magnetic tape 701 during the reading operation of the reading heads of the storage device 7.

The part of the logic 6 required for the printing operation is not shown in detail, because it can be understood from the mode of operation of the device as a whole, and otherwise is similar to the part shown in FIG. 6 with the flow of information passing in the opposite direction. Besides the two information outputs at which the colour information stored in tracks 1, 3 or 2, 4 appear, the logic 6 possesses an end of line output and a y/2 output, at each of which signals appear when an end of line symbol 705 or a y/2 symbol 709 (cf. FIGS. 30, b) are read out by means of the reading heads at the end of an information block 703. The end of line output of the logic 6 is connected via an OR member 561 and an OR member 562 arranged after this on the one hand with the stop input of the storage unit 7 and on the other hand with the start input ofa clock generator 563. The y/2 output of the logic 6 leads on the one hand also to the OR member 561 and on the other hand to an input of the storage device 7 which is connected with the switch for switching over from forward travel to return travel or vice versa.

The stroke inputs of the shift registers 551, 553, together with the input of a comparison counter 565 which is set at the number of storage elements of the shift registers, are located on the output of an OR member 567, whereas the stroke inputs of the shift registers 555/557 are connected with the input of a comparison counter 569 corresponding to the comparison counter 565 at the output of an OR member 571. On each input of the OR members 567 and 571 there is connected the output of the clock generator 563 (rapid stroke, for example 40 KHZ) and at each other input there is connected an AND member 573 or 575. Each input of the AND members 573, 575 is connected to a printer stroke output of the central control unit 8. The other input of the AND member 573 is connected to the output 01 of a flipflop 577, the output Q2 of which is connected with the other input of the AND member 575. The input S1 of the flipflop 577 is connected to an end of printing output and its input S2 is connected to a motif connection output of the central control unit 8.

The third inputs of the OR members 567, 571 are finally connected with an output of the storage device 7 which supplies the read stroke for the tracks 1 to 6. To this output there is fed, for example, by a switching arrangement which is usual in commercial magnetic tape recorders a stroke signal whenever the word just read from the magnetic tape 701 has a binary 1" in at least one place. Since according to the table given above in connection with FIG. 3 each word recorded on the magnetic tape 701, regardless of whether it is dealing with a colour or a special symbol, possesses a binary 1 in at least one place, in the example of execution described here when each stored word is read out a stroke signal is produced, whereas when reading out an empty block 713 (cf. FIG. 3) from the commencement of the reading of the synchronisation symbol in track 9 up to the commencement of the reading of the following synchronisation signal no stroke signals are produced on the read strobe output. The magnetic tape 701 therefore runs away over the empty block during the printing operation at the commencement of the return travel.

A further start output of the central control unit 8 is connected with an input of an OR member 576, the output of which leads to the start input of the storage device 7.

The outputs of the comparison counters 565 and 569 are connected with the stop input of the clock generator 563 so that this is stopped by every comparison/- counter/printing signal (cf. FIG. 4b). Furthermore these outputs are connected to the return inputs of the two comparison counters.

The information carrier 559 possesses a start input which is connected with a further output A of the comparison counter 569. This output A can be adjusted manually to any value of the comparison counter 569, so that the information barrier 559 is switched on at any desired counter position. The information barrier 559 is switched once again to through passage by each successive MZA signal.

The outputs of the shift registers 551, 555 are connected via an OR member 579, those of the shift registers 553, 557 are connected via an OR member 581 to the coding and decoding unit 4, from which the decoded information is fed via the shift registers l1, 12 to the printer 9, which prints out the design pattern 10.

The part of the temporary storage 5 required for the printing operation also possesses a device by means of which, after setting the corresponding address, each desired information block on the magnetic tape 701 can be started in a search run. This device contains a double key 583 which on the one hand adjusts the central control unit to printing and on the other hand adjusts the magnetic tape drive to continuous running. The signal appearing via an AND member 585 sets the output Q2 of a flipflop 587, which switches the magnetic tape drive and can be switched via the OR member 576, even if stop signals are fed to the stop input via the end of line output or y/2 output of the logic 6.

The desired address is provided by means of a binary counter 589 by setting the number of lines. With the binary counter there is connected a comparator 591, to the information input of which there are fed the address bits taken from an output A of the storage device 7. Furthermore, an address counter 593 is provided, the output of which, with its own resetting input R, is connected with the resetting input R of the compararor 591 and the input S1 of the flipflop 595. The address counter 593 is set at the number of bits per address.

The stroke inputs of the comparator 591 and of the address counter 593 have fed to them stroke signals via an AND member 597 when this has been prepared via the output Q2 of the flipflop 595. The input S2 of the flipflop is connected with an output A of the logic 6, via which the A signals are fed in. The other input of the AND member 597 is connected with an output B of the storage device 7, from which the read strobe of tracks 7 or 8 are taken as stroke inpulses.

The mode of operation of this device is as follows. After a given address has been set in the binary counter 589 and after the flipflops 587 and 595 have been set at the outputs Q1, the key 583 is operated, as a result of which the magnetic tape drive is started. At the start, the magnetic tape can be located in any position. With the rear flank of each A signal the AND member 597 is prepared, so that the successive read strobe impulses push the address announced by the A signal into the comparator 591. If this does not indicate any identity with the address standing in the binary counter 589, the address counter 593, the comparator 591 and the flipflop 595 are set back by the last stroke impulse of the output B.

When the next A signal appears, the same processes take place. If when the desired address is reached, identity is confirmed by the comparator 591, then via its output the magnetic tape is stopped and the flipflop 587 is set back, by which means the search run is ended. As the address of an information block 703 is located in each case at the end of the preceding information block, the recording/reading heads of the storage unit 7 are now located immediately in front of the addressed information block so that the temporary storage can be switched over to scanning and a new line can be scanned and stored.

On the basis of FIGS. 8, 8a and 8b the central control unit 8 is described below which controls the progress of all operations which take place during the scanning and printing or storing or reading of the information into or out of the storage unit 7. The centrai control unit 8 thus comprises not only all the devices for producing the various start, stop, stroke and synchronisation signals, but also those devices which are necessary for adaptation to artists drawings 1, design patterns 10 of different sizes or sizes of screen dots.

The central control unit 8 contains as essential parts the step motor 107 for driving the carriage 105 in the Y direction and the synchronous motor 109 for driving the drum 101 in the X direction (cf. also FIG. 2). There are allocated to the step motor 107 a Y screen gauge counter 801 (referred to below as the YRMZ counter) and a Y screen point counter 802 (referred to below as the YRZ counter). With the YRMZ counter it is possibie to adjust the size of a scanning or printing point in the Y direction, whereas with the YRZ counter 802 it is possible to set the number of screen dots of the artist's drawing in the Y direction. Accordingly there are allocated to the synchronous motor 109, which arranges for the transportation of the artists drawing or pattern in the X direction, an XRMZ counter 803 (X screen gauge counter) and an XRZ counter 804 (X screen dot counter).

The different signals fed to the counters or motors are derived from ajoint rectangular generator 805. The generator 805 is connected via a frequency converter 807 with the synchronous motor 109. Between the generator 805 and the frequency converter 807 there is inserted in addition a 2:l divider 811 when a key scanning" 809 is depressed and a 5:1 divider 812 when a key printing 810 is depressed. The result of this is that the drum 101 during the scanning operation is driven at a higher rotation speed than during the printing operation. Between the two dividers 811 and 812 and the frequency transformer 807 there are also inserted two AND members 813 and 814 and also an OR member 816. The drum 101 is driven completely uniformly by the synchronous motor 109.

For scanning the artists drawing 1 or for printing the design pattern 10 in the X direction, a scanning stroke or a printing stroke are derived from the generator 805. For this purpose the generator 805 is connected via a 2:1 divider 817 with the input E of the XRMZ counter 803, the output A of which on the one hand is connected directly with the input of an AND member 819 and on the other hand via a 5:1 divider 821 with the input of an AND member 823. The other input of the AND member 819 is connected with the scanning key 809 and the other input of the AND member 823 is connected with the printing" key 810. The outputs of the AND members 819 and 823 lead to two connecting terminals AT (scanning stroke) and DT (printing stroke), which are arranged on a connecting plate 825.

The divider 817 is released or blocked by a releasing circuit 827. The release is effected via an AND circuit 829, to the one input of which there is connected a general starting key 833 via a delayed action stage 831, whereas its other input is connected with the scanning device 121 (cf. FIG. 2). The starting key 833 also leads via an OR circuit 837 to a connecting terminal ST (Start), whereas the output from the scanning device 121 leads to a connecting terminal MZA (mechanical line commencement). The blocking of the divider 817 is carried out via an OR circuit 839, the one input of which is connected with the output of an AND circuit 841, the one input of which leads to the key scanning 809 and its other input leads to the output A of the XRZ counter 804. Connected to the other input of the OR circuit 839 is the output of an AND circuit 843, the one input of which is connected with the printing key 810 and the other input of which is connected with a connecting terminal DE (end of printing).

The AND circuits 819 and 823 are connected via an OR circuit 845 with the input E of the XRZ counter 804, the restoring input R of which is connected via an OR circuit 847 with the output A of the XRZ counter 804 and the connecting terminal DE. The output of the XRZ counter 804 is also connected to the input of a circuit 850, which is referred to below as X-Test and is described in detail later on on the basis of FIG. 8b.

In addition, the signals which appear at the output of the XRZ counter 804 are fed via an OR circuit 851 to the restoring input of the XRMZ counter 803, to the one input of each AND circuit 853 and 854 and finally to the input S2 of flip flop 855.

The output Q2 of the flip-flop 855 leads together with an outpub B of the XRZ counter 804 via an AND circuit 857 either to the connecting terminal DE end of printing or via the OR circuit 837 to the connecting terminal ST. The input S1 of the flip-flop 855 is connected with the connecting terminal MZA which is also connected to the input S1 of a flip-flop 859, whose output O1 is connected with the other input of the AND circuit 853, the output of which leads to a connecting terminal ZE (end of line), to the input E of the YRZ counter 802, to an input of an AND circuit 861 and finally to an input of an AND circuit 863, the other input of which is connected to the key 809. The output Q2 of the flip-flop 859 is connected on the one hand with the one input of an AND circuit 865, the output of which leads via the OR circuit 845 to the input E of the XRZ counter 804 and whose other input is connected with a connecting terminal ZT (counter stroke), and on the other hand with the other input of the AND circuit 854, the output of which goes to a connecting terminal ZS (counter stop).

The other input of the AND circuit 861 is connected with the printing key 810. Its output leads to a connecting terminal RA (connection of motif). The input S2 of the flip-flop 859 is connected with a connecting terminal VZA (comparison counter/scanning).

The drive of the stepped motor 107 takes place from the generator 805 via a 2:1 divider 868, a 64:1 divider 869 arranged after this and a storage counter 871 arranged after this, whose output A is connected with its restoring input R. The divider 869, which feeds its output signals also to the input E of the YRMZ counter 801, is released or blocked from time to time by a release circuit 873. The release takes place on the one hand via the output Q1 of a flip-flop 875 which is connected with the one input of an AND circuit 877, and on the other hand via a delayed action stage 879, which is connected with the other input of the AND circuit 877. The input of the delayed action stage 879 is connected with an OR circuit 881, on the inputs of which there are located the AND circuits 843 and 863. The blocking of the divider 869 and the restoration of the YRMZ counter 801 take place via the output A of the YRMZ counter 801.

The YRZ counter 802 possesses three outputs, namely one output y/2, which is decoded to one half of the number of lines of the artists drawing 1, an output B which is decoded to the end switching off, and an output UZ (odd number of lines), the meaning of which will be explained later on on the basis of FIG. 8a.

The output y/2 is connected with a connecting terminal y/2 of the connecting plate 825, with the input E of a counter 883 and with the restoring input R of the YRZ counter 802. The output of the counter 883 leads together with the key 810 and the output B of the YRZ counter 802 to the three inputs of an AND circuit 885, the output of which leads on the one hand via an OR circuit 887 and a delayed action stage 889 to a connecting terminal E (end switching off) and on the other hand only via the OR circuit 887 to the restoring input R of the counter 883 and to the input S1 of a flip-flop 891, the input S2 of which is connected with the T 833. The output Q2 of the flip-flop 891 is connected with an input each of the AND circuits of 813 and 814. Also the output A of the counter 883 leads together with the key 809 to the two inputs of an AND circuit 893, which is connected with the other input of the OR circuit 887.

The output UZ of the YRZ counter is connected with the input S2 of the flip-flop 875 and with a connecting terminal UZ (odd number of lines). The YRZ counter also possesses an input MZA which is connected with the connecting terminal MZA.

The YRZ counter 802 represented once again diagrammatically in FIG. 8a is constructed in such a way that when there is an even number of lines after scanning or printing the line y/2 it produces a first y/2 signal and after scanning or printing the last line it produces a second y/2 signal. It differs from the other counters in that it counts upwards not to the figure set, but twice to one half of the figure set. In order to achieve this, a special decoding of the individual decades can be selected. The further mode of operation of the YRZ counter 802 is to be seen from the substitution diagram of FIG. 8a.

When preselecting an even number the key 8023 is not depressed, as a result of which a flip-flop 8025 connected after the AND circuit 8021, the output Q2 of which is connected with the output UZ, remains permanently set at its output Q1. When the counter is adjusted, for example, to the number 20" and the countering cycle begins at 1 then the YRZ counter is adjusted to the number 2" by the ZE signal, end of line signal, appearing after the scanning of the first line. At the end of the scanning of the tenth line, the YRZ counter, because it is decoded at 10", is set back to the number 1" with the indication of a y/2 signal, so that it beings to count once again and after scanning the twentieth line it is set back whilst emitting the second y/2 signal.

In addition the YRZ counter 802 is decoded in such a way that when it is set at an odd number of lines it counts up twice up to the number Y/2+l/2. Furthermore, when it is set at an odd number of lines there occurs at one input of the AND circuit 8021 a 1, because the key 8023 is depressed. This has the consequence that the counter, after scanning the line y/2+1/2 once again gives a y/2 signal extending over the duration of scanning of the next line but also is set at its output Q2 by the y/2 signal of the flip-flop 8025, so that a l occurs at the output UZ during the duration of the whole of the next line.

Let it be assumed that the YRZ counter is adjusted to the number 21 as a result of which the key 8023 is depressed automatically. In this case the YRZ counter is not decoded at 10.5, but at y/2+1/2 11. Consequently first of all 11 full lines of the artists drawing are scanned before the y/2 signal appears, as a result of which the storage device 7 is switched over from forward running to return running. As a result of the U2 signal appearing at the same time as the y/2 signal, in FIG. 8 the flip-flop 875 is set at its output O2, so that the ZE signal, end of line signal, which also appears at the same time as the y/2 signal and which is delayed by the delayed action stage 879, does not reach the release circuit 873. As the U2 signal disappears together with the y/2 signal only after the appearance of the next end of line signal, this operation cannot be upset even by a MZA signal appearing in the meantime. According to FIG. 5, the UZ signal is also fed to the logic 6 in order to suppress any recordings on the magnetic tape 701 during the renewed scanning of the eleventh line, which corresponds to recording an empty block.

The consequence of this is that after scanning the eleventh line the stepped motor 107 is not set in motion and the eleventh line is scanned once again.

Because of this design of the YRZ counter 802 the second y/2 signal is not produced until the end of the twenty-second line in the case of an odd number of lines. Because of the double scanning of the eleventh line, however, this corresponds to the scanning of exactly twenty-one lines, for which the YRZ counter 802 is set.

During printing it is possible for more or less the same operation to take place; i.e., when the UZ signal appears, as is represented in FIG. 8, one could block for the duration of one line on the one hand the Y advance and on the other hand by a connection to the storage unit 7 (cf. FIG. 7) the further movement of the magnetic tape. However, there is also the possibility during printing to use an entirely normal YRZ counter because the empty block after switching over from forward travel to return travel and after renewed starting of the tape would run past the reading heads without effect until the next following information block is read out without a fresh stoppage of the tape. The YRZ counter 802 therefore in the main only decides whether an empty block 703 is to be recorded or not on the magnetic tape 701.

In FIG. 8 the X-Test circuit 850 is shown in diagrammatical form. According to FIG. 8 its inputs are connected with the outputs of the XRZ counter 804 or the scanning device 123. The output of the XRZ counter 804 leads to one input each of AND circuits 8501 and 8503 and via a reversing stage 8505 with the input of an AND circuit 8507. The outputs of the AND circuits are connected with the inputs S2 of each flip-flop 8509, 8511 and 8513. The outputs Q2 of these flip-flops lead to lamps 8515, 8517 and 8519. The output Q2 of theflip-flop 8509 is connected via a reversing stage 8521 with an input of the AND circuit 8507 and, as is also the case with the output Q2 of the flip-flop 8511, via an OR circuit 8523 and a reversing stage 8525 with an input of the AND circuit 8503. Between the scanning device 123 and the the one input of the AND circuit 8501 there is also a reversing stage 8527. The inputs S1 of the flip-flops are connected with the connecting terminal MZA.

The X-Test circuit 850 is intended to ensure that the scanning of an artists drawing 1 begins exactly at the desired commencement of line or ends at the desired end of line. The exact beginning at the commencement of line is ensured during the scanning operation by the MZA signal, after the marking 117 (FIG. 2) has been accurately adjusted whilst the drum 101 is standing still. Whether the scanning ceases exactly at the end of line determined by the marking 119 (FIG. 2) depends on the adjustment of the XRMZ counter 803, because the number of screen dots per line, which is set by the XRZ counter 804, is determined in advance by the desired repeat or the desired number of dots per line. By means of the XRMZ counter 803, therefore, before commencing the scanning the width of a screen dot in the direction of the line must be adjusted in such a way that the total width of all the screen dots corresponds exactly to a line length.

As the XRMZ counter 803 can be adjusted very finely, first of all an approximate calculation is made as to the value at which it will have to be set. Then the drum 101 is set in motion by pressing the starting key 833 (FIG. 8). The Y step motor 107 can remain switched on or else it can be switched off.

After the arrival of an MZA signal (cf. FlG. 8) which sets all the flip-flops in FIG. 8b at their output Q1, the divider 817 is released in conjunction with the key scanning 809, as a result of which the XRMZ counter 803 begins to count. When the number which has been set is reached, the XRZ counter 804 is put forward one step which means that the first dot of the screen is scanned. After the scanning of all the dot points set by the XRZ counter 804, if the XRMZ counter 803 has been properly adjusted, a signal appears at the output A of the XRZ counter 804 exactly simultaneously with the MZE signal of the same length of the scanning device 123. If the two signals appear simultaneously, then the lamp 8519 lights up because the flip-flop 8513 is set to the commencement Q2. On the other hand, the two lamps 8515 and 8517 do not light up, because for the duration of the XRZ signal the AND circuit 8507 and for the duration of the MZE signal the AND circuit 8501 do not let through any signal to the relevant flip-flops.

If the XRZ signal appears before the MZE signal, then the lamp 8515 lights up, because before the appearance of the MZE signal at both inputs of the AND circuit 8501 there occurs a l The two other lamps do not light up because the flip-flops are set in each case with the rear flank of impulses and when this rear flank appears the flip-flop 8509 is already set so that at each input of the AND circuits 8507 and 8505 a 0" occurs when the MZE signal arrives. Something similar applies to the case where the XRZ signal arrives later than the MZE signal. In this case only the lamp 8517 lights up.

When the lamp 8515 lights up the width of each screen dot must be increased by a small amount so that by adjusting the XRMZ counter 803 to a larger number the XRZ signal appears somewhat later. Conversely the XRMZ counter 803 must be set at a smaller number if the lamp 8517 lights up. The more finely the XRMZ counter can be adjusted, the more accurately can the appearance of the XRZ signal be adapted to the appearance of the MZE signal; in the ideal case this can be carried out up to a value which is smaller than the width of the signals MZE or XRZ.

In the device according to the invention a Y-Test corresponding to the X-Test is not absolutely necessary. When starting up the apparatus, first of all the scanning head 2 is adjusted to the first line of the artists drawing 1 stretched on the drum 101. Then the YRMZ counter 801 is adjusted to the Figure calculated and the central control unit is started up with the synchronous motor 109 switched off. By this means in a trial run the carriage is moved to beyond the last line of the artists drawing. If the YRMZ counter is correctly adjusted, the scanning head remains exactly over the last line. If this is not the case, then fresh trial runs are carried out with an altered adjustment of the YRMZ counter until the number set is correct.

Contrary to the X-Test, the Y-Test can be carried out with the drum 101 at a standstill, so that an automaticaly operating device would be superfluous for it. The accurate visual adjustment to a given point of the surface of the drum is facilitated by an eyepiece with crossed threads and a circle surrounding the crossed threads, the circle visible in the eyepiece rendering accurately visible that range of the drum which is comprised by the lens of the scanning head.

The adjustment of the screen size can be carried extraordinarily accurately with the help of the storage counter 871 and the YRMZ counter 801. The storage counter avoids an addition of the error which is unavoidable by adjusting the YRMZ counter 801 per screen dot, so that after each Y advance carried out, the total error is less than a motor step. If a motor step corresponds to an advance of the carriage 105 of 0.05 mm, then the total error at any point in the artists drawing 1 is always smaller than 0.05 mm. The storage counter 871 can have a fixed adjustment or it can be adjustable. When one uses an adjustable storage counter 871, the YRMZ counter 801 can have a fixed adjustment.

The mode of operation of the part of the device according to the invention which is essential for scanning an artists drawing 1 will be described below on the basis of FIGS. 4a, 5, 6 and 8. 

1. In combination a device for sweeping over a sheet, comprising: a support for holding the sheet; a carriage on which is mounted a sweeping means; first driving means for generating continuous relative motion between said support and said carriage in a first direction; second driving means for generating stepwise relative motion between said support and said carriage in a second direction; an electronic trigger signal generating means coupled to said sweeping means for detecting with said sweeping means individual points of said support; a first release means coupled with said trigger signal generating means for releasing a given number of said trigger signals during successive first release cycles; first selecting means coupled with said trigger signal generating means and said first releasing means for preselecting the number and the repetition frequency of the trigger signals released during each first release cycle; a second release means coupled with said second driving means for releasing said stepwise motion during second release cycles, said second release cycles alternating with said first release cycles; and second selecting means coupled with said second driving means for preselecting the length of motion during each second release cycle.
 2. A device according to claim 1 wherein said sheet is a colored pattern and said sweeping means is an opto-electronic scanning head for generating electrical signals characteristic of the colors of said pattern.
 3. A device according to claim 2, including a storage means coupled with said scanning means.
 4. A device according to claim 1 wherein said sheet is a sheet of paper and said sweeping means is a printing means for printing a colored pattern on said paper by receiving electrical signals characteristic of the colors of said pattern.
 5. A device according to claim 4, wherein said support is a drum and the printing means is provided with spaced printing tips along the periphery of the drum.
 6. A device according to claim 4, said printing means is a electro-magnetic printing means having printing pins being fastended to plunger coils of electromagnets.
 7. A device according to claim 4, wherein said printing means is actuated for printing dots.
 8. A device according to claim 4, wherein said printing means is actuated for printing lines.
 9. A device according to claim 4, including a storage means coupled with said printing means.
 10. A device according to claim 1, including means for deriving an electrical signal from said continuous relative motion and coupled with said first release means such that said signal starts each first release cycle.
 11. A device according to claim 1, wherein said first selecting means includes first adjustable counter means for counting said trigger signals and coupled with said first release means such that each first release cycle is ended after a preselected number of trigger signals.
 12. A device according to claim 11, wherein said first selecting means includes a second adjustable counter means for preselecting the repetition frequency of the trigger signals.
 13. A device according to claim 1, wherein the second driving means comprise a step-motor mounted on said carriage.
 14. A device according to claim 13, said second driving means further including step signal generating means coupled with said step-motor.
 15. A device accoRding to claim 14, said second selecting means including third adjustable counter means coupled with said step signal generating means for preselecting the number of step signals fed to said step-motor.
 16. A device according to claim 15, said third counter means being a memory counter.
 17. A device according to claim 14, including a fourth adjustable counter means for counting the step signals and coupled with said second release means such that a second release cycle is ended after a preselected number of step signals.
 18. A device according to claim 1, including adjustable counter means coupled to said second release means such that a second release cycle is started after a predetermined number of trigger signals.
 19. A device according to claim 1, including checking means for visually checking the adjusted repetition frequency of said trigger signals.
 20. A device according to claim 19, wherein said checking means includes counter means for counting the trigger signals and deriving means for deriving an electrical signal from a marking on said support.
 21. A device according to claim 20, wherein said checking means is provided with three lamps, one lamp lights up for simultaneous appearance of the signal derived from said deriving means and a signal derived from said counter, and the other two light up when the signal derived from said deriving means appears either too early and too late with respect to the signal derived from said counter.
 22. A device according to claim 1, wherein said support is a revolving drum.
 23. A device according to claim 22, wherein said carriage is movable in the direction of the drum axis.
 24. A device according to claim 22, wherein said first driving means includes a synchronous motor coupled to a shaft of the drum.
 25. A device according to claim 24, wherein said first driving means includes a pulse transducer coupled to said synchronous motor.
 26. A device according to claim 22, wherein said sheet is so mounted on the drum periphery that part of the latter remains free.
 27. A device according to claim 26, including means for starting and ending said second release cycles only when the uncovered part of the drum periphery passes the sweeping means.
 28. A device according to claim 1, wherein said support is a revolving drum including means for changing the angular speed of said drum for scanning and printing operations.
 29. A device according to claim 1, wherein said trigger signals, said step signals and the signals fed to said synchroneous motor are derived from a common electronic trigger generator.
 30. A device, comprising in combination: a drum for holding a sheet; a carriage for interchangeably mounting a scanning means and a printing means; driving means for continuously revolving the drum; step motor means for the stepwise shifting of the carriage in a direction parallel to the axis of the drum; a trigger signal generating means interchangeably coupled to said scanning means and said printing means for generating scanning and printing signals; a first release means coupled with said trigger signal generating means for releasing a given number of trigger signals during successive first release cycles; first selecting means coupled with said trigger signal generating means and said first releasing means for preselecting the number and the repetition frequency of said trigger signals during each first release cycle; a second release means coupled with said step motor means for releasing said stepwise shifting during second release cycles; and second selecting means coupled with said step motor means for preselecting the number of stepping signals fed to the step motor means during each second release cycle. 